Incidence, treatment and outcome of central nervous system relapse in adult acute lymphoblastic leukaemia patients treated front-line with paediatric-inspired regimens: A retrospective multicentre Campus ALL study.

Within the Campus ALL network we analyzed the incidence, characteristics, treatment and outcome of a central nervous system (CNS) relapse in 1035 consecutive adult acute lymphoblastic leukemia (ALL) patients treated frontline with pediatric-inspired protocols between 2009 and 2020. Seventy-one patients (6.8%) experienced a CNS recurrence, more frequently in T- (28/278; 10%) than in B-ALL (43/757; 5.7%) (p = 0.017). An early CNS relapse-< 12 months from diagnosis-was observed in 41 patients. In multivariate analysis, risk factors for early CNS relapse included T-cell phenotype (p = <0.001), hyperleucocytosis >100 × 109 /L (p<0.001) and male gender (p = 0.015). Treatment was heterogeneous, including chemotherapy, radiotherapy, intrathecal therapy and novel agents. A complete remission (CR) was obtained in 39 patients (55%) with no differences among strategies. After CR, 26 patients underwent an allogenic transplant, with a significant overall survival benefit compared to non-transplanted patients (p = 0.012). After a median observation of 8 months from CNS relapse, 23 patients (32%) were alive. In multivariate analysis, the time to CNS relapse was the strongest predictor of a lower 2-year post-relapse survival (p<0.001). In conclusion, in adult ALL the outcome after a CNS relapse remains very poor. Effective CNS prophylaxis remains the best approach and allogenic transplant should be pursued when possible.

Dasatinib-Blinatumomab for Ph-Positive Acute Lymphoblastic Leukemia in Adults.

BACKGROUND: Outcomes in patients with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL) have improved with the use of tyrosine kinase inhibitors. Molecular remission is a primary goal of treatment. METHODS: We conducted a phase 2 single-group trial of first-line therapy in adults with newly diagnosed Ph-positive ALL (with no upper age limit). Dasatinib plus glucocorticoids were administered, followed by two cycles of blinatumomab. The primary end point was a sustained molecular response in the bone marrow after this treatment. RESULTS: Of the 63 patients (median age, 54 years; range, 24 to 82) who were enrolled, a complete remission was observed in 98%. At the end of dasatinib induction therapy (day 85), 29% of the patients had a molecular response, and this percentage increased to 60% after two cycles of blinatumomab; the percentage of patients with a molecular response increased further after additional blinatumomab cycles. At a median follow-up of 18 months, overall survival was 95% and disease-free survival was 88%; disease-free survival was lower among patients who had an IKZF1 deletion plus additional genetic aberrations (CDKN2A or CDKN2B, PAX5, or both [i.e., IKZF1 plus]). ABL1 mutations were detected in 6 patients who had increased minimal residual disease during induction therapy, and all these mutations were cleared by blinatumomab. Six relapses occurred. Overall, 21 adverse events of grade 3 or higher were recorded. A total of 24 patients received a stem-cell allograft, and 1 death was related to transplantation (4%). CONCLUSIONS: A chemotherapy-free induction and consolidation first-line treatment with dasatinib and blinatumomab that was based on a targeted and immunotherapeutic strategy was associated with high incidences of molecular response and survival and few toxic effects of grade 3 or higher in adults with Ph-positive ALL. (Funded by Associazione Italiana per la Ricerca sul Cancro and others; GIMEMA LAL2116 D-ALBA EudraCT number, 2016-001083-11; ClinicalTrials.gov number, NCT02744768.).

Multicenter retrospective analysis of clinical outcome of adult patients with mixed-phenotype acute leukemia treated with acute myeloid leukemia-like or acute lymphoblastic leukemia-like chemotherapy and impact of allogeneic stem cell transplantation: a Campus ALL study.

Mixed-phenotype acute leukemia (MPAL) is a rare disease. Treatment is often similar to that of acute lymphoblastic leukemia (ALL), but the outcome in adults and the role of allogeneic stem cell transplantation (AlloSCT) are not well defined. We report on 77 adult patients diagnosed with MPAL over the last 10 years and treated with a curative intent. Median age was 49 years; 7.6% of cases had a BCR::ABL1 rearrangement. Thirty patients (39%) were treated with an acute myeloid leukemia (AML)-like induction and 47 (61%) with an ALL-like scheme. The complete remission (CR) rate was 67.6% and an ALL-like therapy was associated with a better CR rate (P = 0.048). The median OS was 41.9 months; age ≤ 60 years was associated with a better OS (67 vs 26 months, P = 0.014). An AlloSCT was performed in 50 patients (65%). The 5-year OS of transplanted patients was 54%. The OS post-AlloSCT was better in patients who were minimal residual disease (MRD)-negative prior to transplant (75.8% vs 45.2%, P = 0.06). This study shows that MPAL patients respond better to an ALL-like induction therapy; that consolidation therapy should include, whenever possible, an AlloSCT and that MRD negativity should be a primary endpoint of treatment.

MYB rearrangements and over-expression in T-cell acute lymphoblastic leukemia.

We investigated MYB rearrangements (MYB-R) and the levels of MYB expression, in 331 pediatric and adult patients with T-cell acute lymphoblastic leukemia (T-ALL). MYB-R were detected in 17 cases and consisted of MYB tandem duplication (tdup) (= 14) or T cell receptor beta locus (TRB)-MYB (= 3). As previously reported, TRB-MYB was found only in children (1.6%) while MYB tdup occurred in both age groups, although it was slightly more frequent in children (5.2% vs 2.8%). Shared features of MYB-R T-ALL were a non-early T-cell precursor (ETP) phenotype, a high incidence of NOTCH1/FBXW7 mutations (81%) and CDKN2AB deletions (70.5%). Moreover, they mainly belonged to HOXA (=8), NKX2-1/2-2/TLX1 (=4), and TLX3 (=3) homeobox-related subgroups. Overall, MYB-R cases had significantly higher levels of MYB expression than MYB wild type (MYB-wt) cases, although high levels of MYB were detected in ~ 30% of MYB-wt T-ALL. Consistent with the transcriptional regulatory networks, cases with high MYB expression were significantly enriched within the TAL/LMO subgroup (P = .017). Interestingly, analysis of paired diagnosis/remission samples demonstrated that a high MYB expression was restricted to the leukemic clone. Our study has indicated that different mechanisms underlie MYB deregulation in 30%-40% of T-ALL and highlighted that, MYB has potential as predictive/prognostic marker and/or target for tailored therapy.

A multicenter total therapy strategy for de novo adult Philadelphia chromosome positive acute lymphoblastic leukemia patients: final results of the GIMEMA LAL1509 protocol.

The GIMEMA LAL1509 protocol, designed for adult (≥18-60 years) de novo Ph+ acute lymphoblastic leukemia patients, was based on a dasatinib plus steroids induction - with central nervous system prophylaxis - followed by dasatinib alone in patients in complete molecular response or chemotherapy and/or allogeneic transplantation in patients not reaching a complete molecular response. Sixty patients (median age 41.9 years) were enrolled: 33 were p190+, 18 p210+ and 9 p190/p210+. At the end of induction (day +85), 58 patients (97%) achieved a complete hematologic remission. No deaths in induction were recorded. Eleven patients (18.3%) obtained a complete molecular response. Among non-complete molecular responders (n=47), 22 underwent an allogeneic transplant. Seventeen hematologic relapses occurred (median 7 months, range 3-40.1), 13 during consolidation and 4 post-transplant. ABL1 mutations (5 T315I, 3 V299L, 1 E281K and 1 G254E) were found in 10/13 relapsed cases. With a median follow-up of 57.4 months (range: 4.2-75.6), overall survival and disease-free survival are 56.3% and 47.2%. A better diseasefree survival was observed in patients who obtained a molecular response at day +85 compared to cases who did not. The presence of additional copy number aberrations - IKZF1 plus CDKN2A/B and/or PAX5 deletions - was the most important unfavorable prognostic factor on overall and disease-free survival (p=0.005 and p=0.0008). This study shows that in adult Ph+ ALL long-term survivals can be achieved with a total-therapy strategy based on a chemo-free induction and, in complete molecular responders, also without further systemic chemotherapy. Finally, the screening of additional copy number aberrations should be included in the diagnostic work-up. EudraCT 2010-019119-39.

Philadelphia-like acute lymphoblastic leukemia is associated with minimal residual disease persistence and poor outcome. First report of the minimal residual disease-oriented GIMEMA LAL1913.

Early recognition of Ph-like acute lymphoblastic leukemia cases could impact on the management and outcome of this subset of B-lineage ALL. To assess the prognostic value of the Ph-like status in a pediatric-inspired, minimal residual disease (MRD)-driven trial, we screened 88 B-lineage ALL cases negative for the major fusion genes (BCR-ABL1, ETV6-RUNX1, TCF3-PBX1 and KTM2Ar) enrolled in the GIMEMA LAL1913 front-line protocol for adult BCR/ABL1-negative ALL. The screening - performed using the BCR/ABL1-like predictor - identified 28 Ph-like cases (31.8%), characterized by CRLF2 overexpression (35.7%), JAK/STAT pathway mutations (33.3%), IKZF1 (63.6%), BTG1 (50%) and EBF1 (27.3%) deletions, and rearrangements targeting tyrosine kinases or CRLF2 (40%). The correlation with outcome highlighted that: i) the complete remission (CR) rate was significantly lower in Ph-like compared to non-Ph-like cases (74.1% vs 91.5%, p=0.044); ii) at time point 2 (TP2), decisional for transplant allocation, 52.9% of Ph-like cases vs 20% of non-Ph-like were MRD-positive (p=0.025); iii) the Ph-like profile was the only parameter associated with a higher risk of being MRD-positive at TP2 (p=0.014); iv) at 24 months, Ph-like patients had a significantly inferior event-free and disease-free survival compared to non-Ph-like patients (33.5% vs 66.2%, p=0.005 and 45.5% vs 72.3%, p=0.062, respectively). This study documents that Ph-like patients have a lower CR rate, EFS and DFS, as well as a greater MRD persistence also in a pediatric-oriented and MRD-driven adult ALL protocol, thus reinforcing that the early recognition of Ph-like ALL patients at diagnosis is crucial to refine risk-stratification and to optimize therapeutic strategies.

Adolescent and young adult acute lymphoblastic leukemia. Final results of the phase II pediatric-like GIMEMA LAL-1308 trial.

Adolescents and young adults (AYA) with acute lymphoblastic leukemia (ALL) represent a unique patient population with specific characteristics and needs. Growing evidences suggest that pediatric-inspired approaches improve the outcome in AYA. These results prompted the design of a pediatric AIEOP-BFM ALL 2000-based regimen - the GIMEMA LAL-1308 protocol - for newly diagnosed AYA (range 18-35 years) with Philadelphia negative (Ph-) ALL. The protocol included minimal residual disease (MRD) analysis at two different time-points (TP), that is, at the end of induction IA and consolidation IB, and a modulation in post-consolidation intensity according to MRD. Seventy-six patients were eligible between September 2010 and October 2014. The regimen was well tolerated, with 2.7% induction deaths and no deaths in the post-consolidation phase. The complete response (CR) rate was 92%; the 48-month overall survival (OS) and disease-free survival (DFS) were 60.3% and 60.4%. Both OS and DFS were significantly better in T-ALL than B-ALL. A molecular MRD <10-3 at TP1 was associated with a significantly better OS and DFS (77% vs 39% and 71.9% vs 34.4%, respectively);similar results were documented at TP2 (OS and DFS 74.5% vs 30.6% and 71.5% vs 25.7%, respectively). The LAL-1308 results were compared to those from similar historic AYA populations undergoing the two previous GIMEMA LAL-2000 and LAL-0904 protocols. Both OS and DFS improved significantly compared to the two previous protocols. These results indicate that this pediatric-inspired and MRD-oriented protocol is feasible and effective for Ph- AYA ALL patients, and underline the prognostic value of MRD determinations at specific TPs.

Nelarabine as salvage therapy and bridge to allogeneic stem cell transplant in 118 adult patients with relapsed/refractory T-cell acute lymphoblastic leukemia/lymphoma. A CAMPUS ALL study.

The outcome of relapsed or refractory (R/R) T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/T-LBL) in adults is poor, with less than 20% of patients surviving at 5 years. Nelarabine is the only drug specifically approved for R/R T-ALL/T-LBL, but the information to support its use is based on limited available data. The aim of this observational phase four study was to provide recent additional data on the efficacy and safety of nelarabine in adults with R/R T-ALL/T-LBL and to evaluate the feasibility and outcome of allogeneic hematopoietic stem cell transplant (SCT) after salvage with nelarabine therapy. The primary endpoints were overall response rate (ORR) and overall survival (OS). Additional endpoints were safety, SCT rate and post-SCT OS. Between May 2007 and November 2018, 118 patients received nelarabine salvage therapy at 27 Italian hematology sites. The median age was 37 years (range 18-74 years), 73% were male, 77 had a diagnosis of T-ALL and 41 of T-LBL, and 65/118 (55%) had received more than two lines of therapy. The median number of nelarabine cycles was two (range 1-4); 43/118 (36%) patients had complete remission (CR), 16 had partial remission (14%) and 59 (50%) were refractory, with an ORR of 50%. The probability of OS, from the first dose of nelarabine, was 37% at 1 year with a median survival of 8 months. The OS at 1 year was significantly better for the 47 patients (40%) who underwent SCT after nelarabine salvage therapy (58% vs 22%, log-rank P < .001). The probability of OS at 2 and 5 years from SCT was 46% and 38%, respectively. Seventy-five patients (64%) experienced one or more drug-related adverse events (AE). Grade III-IV neurologic toxicities were observed in 9/118 (8%) of cases and thrombocytopenia or/and neutropenia (grade III-IV) were reported in 41% and 43% of cases, respectively. In conclusion, this is one of the largest cohorts of adult patients with R/R T-ALL/T-LBL treated in real life with nelarabine. Taking into account the poor prognosis of this patient population, nelarabine represents an effective option with an ORR of 50% and a CR rate of 36%. In addition, 40% of cases following nelarabine salvage therapy could undergo SCT with an expected OS at 2 and 5 years of 46% and 38%, respectively. The safety profile of nelarabine was acceptable with only 8% of cases showing grade III-IV neurological AE.

Prognostic implications of additional genomic lesions in adult Philadelphia chromosome-positive acute lymphoblastic leukemia.

To shed light onto the molecular basis of Philadelphia chromosome-positive acute lymphoblastic leukemia and to investigate the prognostic role of additional genomic lesions, we analyzed copy number aberrations using the Cytoscan HD Array in 116 newly diagnosed adult patients with Philadelphia chromosome-positive acute lymphoblastic leukemia enrolled in four different GIMEMA protocols, all based on a chemotherapy-free induction strategy. This analysis showed that patients with Philadelphia chromosome-positive acute lymphoblastic leukemia carry an average of 7.8 lesions/case, with deletions outnumbering gains (88% versus 12%). The most common deletions were those targeting IKZF1, PAX5 and CDKN2A/B, which were detected in 84%, 36% and 32% of cases, respectively. Patients carrying simultaneous deletions of IKZF1 plus CDKN2A/B and/or PAX5 had a significantly lower disease-free survival rate (24.9% versus 43.3%; P=0.026). The only IKZF1 isoform affecting prognosis was the dominant negative one (P=0.003). Analysis of copy number aberrations showed that 18% of patients harbored MEF2C deletions, which were of two types, differing in size: the longer deletions were associated with the achievement of a complete molecular remission (P=0.05) and had a favorable impact on disease-free survival (64.3% versus 32.1% at 36 months; P=0.031). These findings retained statistical significance also in multivariate analysis (P=0.057). KRAS deletions, detected in 6% of cases, were associated with the achievement of a complete molecular remission (P=0.009). These results indicate that in adults with Philadelphia chromosome-positive acute lymphoblastic leukemia a detailed evaluation of additional deletions - including CDKN2A/B, PAX5, IKZF1, MEF2C and KRAS - has prognostic implications and should be incorporated in the design of more personalized treatment strategies.

Rapid identification of BCR/ABL1-like acute lymphoblastic leukaemia patients using a predictive statistical model based on quantitative real time-polymerase chain reaction: clinical, prognostic and therapeutic implications.

BCR/ABL1-like acute lymphoblastic leukaemia (ALL) is a subgroup of B-lineage acute lymphoblastic leukaemia that occurs within cases without recurrent molecular rearrangements. Gene expression profiling (GEP) can identify these cases but it is expensive and not widely available. Using GEP, we identified 10 genes specifically overexpressed by BCR/ABL1-like ALL cases and used their expression values - assessed by quantitative real time-polymerase chain reaction (Q-RT-PCR) in 26 BCR/ABL1-like and 26 non-BCR/ABL1-like cases to build a statistical "BCR/ABL1-like predictor", for the identification of BCR/ABL1-like cases. By screening 142 B-lineage ALL patients with the "BCR/ABL1-like predictor", we identified 28/142 BCR/ABL1-like patients (19·7%). Overall, BCR/ABL1-like cases were enriched in JAK/STAT mutations (P < 0·001), IKZF1 deletions (P < 0·001) and rearrangements involving cytokine receptors and tyrosine kinases (P = 0·001), thus corroborating the validity of the prediction. Clinically, the BCR/ABL1-like cases identified by the BCR/ABL1-like predictor achieved a lower rate of complete remission (P = 0·014) and a worse event-free survival (P = 0·0009) compared to non-BCR/ABL1-like ALL. Consistently, primary cells from BCR/ABL1-like cases responded in vitro to ponatinib. We propose a simple tool based on Q-RT-PCR and a statistical model that is capable of easily, quickly and reliably identifying BCR/ABL1-like ALL cases at diagnosis.

Clinical significance of recurrent copy number aberrations in B-lineage acute lymphoblastic leukaemia without recurrent fusion genes across age cohorts.

Copy number aberrations (CNAs) represent cooperating events in B-lineage acute lymphoblastic leukaemia (B-ALL); however, their clinical relevance across different age cohorts is unclear. We analysed the recurrent CNAs in 157 age-stratified B-ALL negative cases for recurrent rearrangements (B-NEG ALL), and their association with patients' clinico-biological features. We found that: (i) CDKN2A/RB1-deleted and EBF1-deleted adults had a shorter disease-free survival than those with wild-type, (ii) among the unfavourable markers, CDKN2A/RB1 deletions and K/NRAS mutations retained their impact in multivariate analysis, encouraging the evaluation of CDKN2A/RB1 deletions and RAS mutations in the diagnostic/prognostic workflow to refine ALL risk assessment.

Comparative analysis between RQ-PCR and digital-droplet-PCR of immunoglobulin/T-cell receptor gene rearrangements to monitor minimal residual disease in acute lymphoblastic leukaemia.

Real-time quantitative polymerase chain reaction (RQ-PCR) is a standardized tool for minimal residual disease (MRD) monitoring in acute lymphoblastic leukaemia (ALL). The applicability of this technology is limited by the need of a standard curve based on diagnostic DNA. The digital droplet PCR (ddPCR) technology has been recently applied to various medical fields, but its use in MRD monitoring is under investigation. In this study, we analysed 50 ALL cases by both methods in two phases: in the first, we established analytical parameters to investigate the applicability of this new technique; in the second, we analysed MRD levels in 141 follow-up (FU) samples to investigate the possible use of ddPCR for MRD monitoring in ALL patients. We documented that ddPCR has sensitivity and accuracy at least comparable to those of RQ-PCR. Overall, the two methods gave concordant results in 124 of the 141 analysed MRD samples (88%, P = 0·94). Discordant results were found in 12% borderline cases. The results obtained prove that ddPCR is a reliable method for MRD monitoring in ALL, with the advantage of quantifying without the need of the calibration curves. Its application in a cohort of patients with a longer FU will conclusively define its clinical predictive value.

A sequential approach with imatinib, chemotherapy and transplant for adult Ph+ acute lymphoblastic leukemia: final results of the GIMEMA LAL 0904 study.

In the GIMEMA LAL 0904 protocol, adult Philadelphia positive acute lymphoblastic leukemia patients were treated with chemotherapy for induction and consolidation, followed by maintenance with imatinib. The protocol was subsequently amended and imatinib was incorporated in the induction and post-remission phase together with chemotherapy. Due to the toxicity of this combined approach, the protocol was further amended to a sequential scheme based on imatinib plus steroids as induction, followed by consolidation with chemotherapy plus imatinib and, when applicable, by a hematopoietic stem cell transplant. Fifty-one patients (median age 45.9 years) were enrolled in the final sequential protocol. At the end of induction (day +50), 96% of evaluable patients (n=49) achieved a complete hematologic remission; after consolidation, all were in complete hematologic remission. No deaths in induction were recorded. Overall survival and disease-free survival at 60 months are 48.8% and 45.8%, respectively. At day +50 (end of imatinib induction), a more than 1.3 log-reduction of BCR-ABL1 levels was associated with a significantly longer disease-free survival (55.6%, 95%CI: 39.0-79.3 vs. 20%, 95%CI: 5.8-69.1; P=0.03), overall survival (59.1%, 95%CI: 42.3-82.6 vs. 20%, 95%CI: 5.8-69.1; P=0.02) and lower incidence of relapse (20.5%, 95%CI: 7.2-38.6 vs. 60.0%, 95%CI: 21.6-84.3; P=0.01). Mean BCR-ABL1 levels remained significantly higher in patients who subsequently relapsed. Finally, BCR-ABL1p190 patients showed a significantly faster molecular response than BCR-ABL1p210 patients (P=0.023). Though the study was not powered to evaluate the role of allogeneic stem cell transplant, allografting positively impacted on both overall and disease-free survival. In conclusion, a sequential approach with imatinib alone in induction, consolidated by chemotherapy plus imatinib followed by a stem cell transplant is a feasible, well-tolerated and effective strategy for adult Philadelphia positive acute lymphoblastic leukemia, leading to the best long-term survival rates so far reported. (clinicaltrials.gov identifier: 00458848).

RNA sequencing unravels the genetics of refractory/relapsed T-cell acute lymphoblastic leukemia. Prognostic and therapeutic implications.

Despite therapeutic improvements, a sizable number of patients with T-cell acute lymphoblastic leukemia still have a poor outcome. To unravel the genomic background associated with refractoriness, we evaluated the transcriptome of 19 cases of refractory/early relapsed T-cell acute lymphoblastic leukemia (discovery cohort) by performing RNA-sequencing on diagnostic material. The incidence and prognostic impact of the most frequently mutated pathways were validated by Sanger sequencing on genomic DNA from diagnostic samples of an independent cohort of 49 cases (validation cohort), including refractory, relapsed and responsive cases. Combined gene expression and fusion transcript analyses in the discovery cohort revealed the presence of known oncogenes and identified novel rearrangements inducing overexpression, as well as inactivation of tumor suppressor genes. Mutation analysis identified JAK/STAT and RAS/PTEN as the most commonly disrupted pathways in patients with chemorefractory disease or early relapse, frequently in association with NOTCH1/FBXW7 mutations. The analysis on the validation cohort documented a significantly higher risk of relapse, inferior overall survival, disease-free survival and event-free survival in patients with JAK/STAT or RAS/PTEN alterations. Conversely, a significantly better survival was observed in patients harboring only NOTCH1/FBXW7 mutations: this favorable prognostic effect was abrogated by the presence of concomitant mutations. Preliminary in vitro assays on primary cells demonstrated sensitivity to specific inhibitors. These data document the negative prognostic impact of JAK/STAT and RAS/PTEN mutations in T-cell acute lymphoblastic leukemia and suggest the potential clinical application of JAK and PI3K/mTOR inhibitors in patients harboring mutations in these pathways.

Immunophenotypic and functional characterization of ex vivo expanded natural killer cells for clinical use in acute lymphoblastic leukemia patients.

The management of acute lymphoblastic leukemia (ALL) patients has witnessed profound changes in recent years. Nonetheless, most patients tend to relapse, underlining the need for new therapeutic approaches. The anti-leukemic potential of natural killer (NK) cells has over the years raised considerable interest. In this study, we developed an efficient method for the expansion and activation of NK cells isolated from healthy donors and ALL patients for clinical use. NK cell products were derived from peripheral blood mononuclear cells of 35 healthy donors and 4 B-lineage ALL by immunomagnetic CD3 T cell depletion followed by CD56 cell enrichment. Isolated NK cells were expanded and stimulated in serum-free medium supplemented with irradiated autologous feeder cells and autologous plasma in the presence of clinical grade interleukin (IL)-2 and IL-15 for 14 days. Healthy donor NK cells expanded on average 34.9 ± 10.4 fold and were represented, after expansion, by a highly pure population of CD3(-)CD56(+) cells showing a significant upregulation of natural cytotoxicity receptors, activating receptors and maturation markers. These expanded effectors showed cytolytic activity against K562 cells and, most importantly, against primary adult B-lineage ALL blasts. NK cells could be efficiently isolated and expanded-on average 39.5 ± 20.3 fold-also from primary B-lineage ALL samples of patients in complete remission. The expanded NK cells from these patients showed a significantly increased expression of the NKG2D- and DNAM1-activating receptors and were cytotoxic against K562 cells. These data provide the basis for developing new immunotherapeutic strategies for the management of ALL patients.

Whole-genome amplification for the detection of molecular targets and minimal residual disease monitoring in acute lymphoblastic leukaemia.

Accurate genomic characterization requires sufficient amounts of optimal quality DNA. An approach for increasing the DNA amount is the whole-genome amplification (WGA) method. We applied WGA to the molecular quantification and minimal residual disease (MRD) evaluation of acute lymphoblastic leukaemia (ALL), aiming to compare the results obtained from genomic DNA and amplified DNA with WGA, and to evaluate the applicability and the reliability of WGA-DNA. Twenty paired samples from adult ALL patients were sequenced to identify the functional germline V-D-J segment at diagnosis; real-time quantitative polymerase chain reaction (RQ-PCR) quantitative analysis was performed both at diagnosis and follow-up. Genomic DNA and WGA-DNA screening identified equivalent 87 rearrangements. At diagnosis, the quantitative evaluation of genomic DNA samples showed 1 logarithm difference to WGA-DNA samples; these levels are comparable, being within the degree of acceptability and confidence. In the follow-up samples, RQ-PCR analysis on genomic DNA and WGA showed concordant MRD results in 16/18 samples, while 2/18 were MRD-positive outside the quantitative range by RQ-PCR (i.e. <5 × 10(-5)) on genomic DNA and MRD-negative on WGA-DNA. WGA-DNA enables: (i) the design of accurate targets for MRD evaluation in ALL patients, (ii) accurate disease quantification at diagnosis, (iii) MRD quantification comparable to genomic DNA.

Recognition of adult and pediatric acute lymphoblastic leukemia blasts by natural killer cells.

In this study, we aimed to investigate the pathways of recognition of acute lymphoblastic leukemia blasts by natural killer cells and to verify whether differences in natural killer cell activating receptor ligand expression among groups defined by age of patients, or presence of cytogenetic/molecular aberrations correlate with the susceptibility to recognition and killing. We analyzed 103 newly diagnosed acute lymphoblastic leukemia patients: 46 adults and 57 children. Pediatric blasts showed a significantly higher expression of Nec-2 (P=0.03), ULBP-1 (P=0.01) and ULBP-3 (P=0.04) compared to adult cells. The differential expression of these ligands between adults and children was confined to B-lineage acute lymphoblastic leukemia with no known molecular alterations. Within molecularly defined subgroups of patients, a high surface expression of NKG2D and DNAM1 ligands was found on BCR-ABL(+) blasts, regardless of patient age. Accordingly, BCR-ABL(+) blasts proved to be significantly more susceptible to natural killer-dependent lysis than B-lineage blasts without molecular aberrations (P=0.03). Cytotoxic tests performed in the presence of neutralizing antibodies indicated a pathway of acute lymphoblastic leukemia cell recognition in the setting of the Nec-2/DNAM-1 interaction. These data provide a biological explanation of the different roles played by alloreactive natural killer cells in pediatric versus adult acute lymphoblastic leukemia and suggest that new natural killer-based strategies targeting specific subgroups of patients, particularly those BCR-ABL(+), are worth pursuing further.

Dasatinib as first-line treatment for adult patients with Philadelphia chromosome-positive acute lymphoblastic leukemia.

Dasatinib is a potent BCR-ABL inhibitor effective in chronic myeloid leukemia and Ph(+) acute lymphoblastic leukemia (ALL) resistant/intolerant to imatinib. In the GIMEMA LAL1205 protocol, patients with newly diagnosed Ph(+) ALL older than 18 years (with no upper age limit) received dasatinib induction therapy for 84 days combined with steroids for the first 32 days and intrathecal chemotherapy. Postremission therapy was free. Fifty-three patients were evaluable (median age, 53.6 years). All patients achieved a complete hematologic remission (CHR), 49 (92.5%) at day 22. At this time point, 10 patients achieved a BCR-ABL reduction to < 10(-3). At 20 months, the overall survival was 69.2% and disease-free survival was 51.1%. A significant difference in DFS was observed between patients who showed at day 22 a decrease in BCR-ABL levels to < 10(-3) compared with patients who never reached these levels during induction. In multivariate analysis, BCR-ABL levels of < 10(-3) at day 85 correlated with disease-free survival. No deaths or relapses occurred during induction. Twenty-three patients relapsed after completing induction. A T315I mutation was detected in 12 of 17 relapsed cases. Treatment was well tolerated; only 4 patients discontinued therapy during the last phase of the induction when already in CHR. In adult Ph(+) ALL, induction treatment with dasatinib plus steroids is associated with a CHR in virtually all patients, irrespective of age, good compliance, no deaths, and a very rapid debulking of the neoplastic clone.